Method of making dustless soap powder



United States Patent METHOD OF MAKING DUSTLESS SOAP POWDER Purdy Bradford, Palos Park, Ill., assignor to Swift & Company, Chicago, 11]., a corporation of Illinois No Drawing. Application January 28, 1952, Serial No. 268,684

Claims. (252-3 69) This invention relates in general to improvements in the manufacture of soaps, and more particularly to improvements in the manufacture of powdered, granulated, or finely-divided soaps which are substantially free of objectionable soap dust particles.

Powdered soap often has the disadvantage of the presence of soap dust particles or fines mixed in with the soap powder. The powdered or granulated soap particles readily dissolve in solution to form suds, but the soap dust particles lump together or agglomerate on the surface of the liquid and resist solution. Consequently, soap powders containing such soap dust particles possess undesirable sudsing qualities which adversely affect the marketability of the product. Also, minute soap dust particles, like ordinary dust particles, are capable of being airborne. The consumer, upon opening the soap carton in which soap powder is ordinarily packaged and pouring out the desired amount of soap, often causes to be airborne an appreciable amount of soap dust. These dust particles may be irritating to the mucous membranes of the nose, throat, and eyes, besides representing a loss of soap to the consumer. Furthermore, the soap dust particles or fines tend to settle to the bottom of the carton, presenting the appearance of the carton being incompletely filled.

The usual methods of manufacturing soap powders in the past have been 1) grinding or comminuting the soap to reduce it to powdered form; (2) spray cooling, wherein hot liquid soap capable of crystallization is directed into a cooling air stream; or (3) spray drying, wherein hot liquid soap is sprayed into a current of warm air which'removes the moisture therefrom and causes the liquid soap to solidify into minute particles. In general, attempts to prevent the formation of soap dust particles formed from powdered soaps produced by these methods have been unsuccessful.

An object of the present invention is to provide a method for manufacturing a substantially dustless soap powder. Y

An additional object of the invention is to provide a soap powder which is substantially dustless.

A further object of the invention is to provide a soap powder which is free-flowing, does not agglomerate when added to water, and has a soft feel.

Other objects and advantages of the invention will be apparent as the invention is hereinafter described in more detail.

It has now been discovered that by mixing alkalies with soap flakes, adding thereto a saponifiable higher fatty acid during such mixing and thereafter thoroughly mixing the whole until broken up into well-defined granules, a powdered soap product is obtained which is sub-. stantially dustless, does not agglomerate or lump together when added to water, and has a very soft feel.

More specifically, the method used in forming the dustless soap powder of the present invention comprises adding comminuted soap and alkalies such as sodium phosphate, soda ash, and modified soda to a mixing chamher. Any conventional mixer known to the art may be employed. A saponifiable higher fatty acid such as Neofat S-l42, red oil or the like is then introduced into the mixing chamber either while the soap flakes and alkalies are mixing or after they have been thoroughly mixed. It has been found desirable to add the saponifiable higher fatty acid in small increments, although one or two additions would be satisfactory for a soap powder in which the amount of soap made from this material is not critical. The soap dust particles (with the alkalies mixed therewith), during saponification of the saponifiable higher fatty acid added thereto, agglomerate or unite to form the desired free-flowing, welldefined granules. The resulting product may then be discharged to a suitable screen where it is screened to remove any lumpy material present. The product may then be packaged in the conventional manner to provide a dustless, free-flowing granular product which will not agglomerate upon addition to water.

The following specific examples are provided to 1'1- lustrate the principles of the present invention, but are not to be construed as limitations thereon:

Example I 100 pounds of soap flakes containing per cent actual soap, 5 per cent sodium silicate, 5 per cent soda ash, and 10 per cent water were mixed with 15 pounds of sodium phosphate, 10 pounds of soda ash and 10 pounds of modified soda (a mixture of approximately 38 per cent sodium bicarbonate, 48 per cent sodium carbonate and 14 per cent water). After thorough mixing at room temperature and pressure, 10 pounds of Neofat 5-142 were added and allowed to saponi'fy with continued mixing, also at room temperature and pressure. The re sulting product was then screened to remove any lumpy material present and packaged. The product was substantially free of soap dust and had good solubility in water.

Example I] 142 pounds of soap consisting of 79 per cent dry soap, 2 per cent dry silicate, 14 per cent dry pyrophosphate and 5 per cent water were mixed with 16 pounds of trisodium phosphate and 36 pounds of a commercial preparation of sodium sesqui-carbonate temperature and pressure. No reduction in dustiness of the soap product was noted. Thereafter sufiicient 'red oil was added to the mixture to increase the total concentration of red oil therein to about 5 per cent by weight on the basis of the dry ingredients. After about 30 minutes mixing the red oil had reacted with the alkalies present and a dustless, free-flowing, granular product resulted.

Although the mixing of the ingredients is carried out at room temperature and pressure, the temperature may increase slightly during mixing, due to the heat of saponification. This increase in temperature does not adversely atfect the formation of the free-flowing, granular product in any way.

In carrying out the invention, a sufficient amount of saponifiable higher fatty acid such as Neofat S442, red oil or the like should be added to the mixture to thoroughly wet all of the soap so that, instead of a powdered mixture, the soap has approximately the consistency of wet sawdust. The amount of saponifiable higher fatty acid utilized may vary from about 5 per cent to about 20 per cent by weight, the percentage of Neofat 8-142 used being based upon the soap content of the re- 1 per cent-by weight of red oil based on the dry ingredients was then introsulting mixture and the percentage of red oil utilized being calculated on the basis of the dry ingredients. Although greater percentages of fatty acid could be utilized, 20 per cent fatty acids represents the practical top limit to be used in carrying out the invention.

'The amount of alkali which must be added to the soap flakes to saponify the saponifiable higher fatty acid used depends upon the type of alkali used and upon the saponification value of the particular saponifiable higher fatty acid. For a saponifiable higher fatty acid with saponification value of 200 and sodium carbonate as the saponifying alkali, 53 parts of the carbonate is required for each 282 parts of saponifiable higher fatty acid. If a more alkaline product is desired, caustic soda may be utilized as the saponifying alkali or enough additional alkali may be added .to increase the alkalinity of the soap mixture. The soda ash utilized in the present method .is preferably about .99 per cent commercial :anhydrous sodium carbonate.

The soap content of the compositions treated in accordance with the present invention may range from about 50 per cent to 85 per cent. The particular form of the soap is not limited to flakes but may also include soap chips and powder. The soap particles may be made of various compositions, e. g., sodium or potassium soaps of fatty acids, with or without fillers, builders, emulsifiers, etc., and may be formed by any suitable method, e. g., by granulating milled soap; by drum-drying soap solutions to form flakes and chips; by spraydrying soap solutions to form powder; by spray-cooling.

soap solutions, etc. Examples of fillers and builders which may be used in the soap to be treated are sodium silicate, sodium carbonate, trisodium phosphate, tetras'odium pyrophosphate, and sodium .hexametaphosphate, while desirable emulsifiers include ammonium linoleate, ordinary monoand diglycerides, and sodium 'sulfo acetate derivatives of the monoand diglycerides.

The commercial Neofat 5-142 product used in Example I has the following composition:

' Per cent Oleic acid '46 Linoleic acid 39 Linolenic acid 3 Rosin acids 12 Other similar materials such as red oil or other fatty acids may be used in place of Neofat S442, and in approximately the same proportions as the Neofat. Red oil, which is used in Example II, is otherwise known as commercial oleic acid and is an oil with a color range which varies between light straw and deep red.

It is. composed of approximately 70 per cent oleic acid, the

Rosin acid, otherwise known as abietic acid and a constituent of the Neofat 8-142 product, is an acid of high molecular weight whose sodium and potassium salts have soaplike properties. It is ordinarily added to the sodium salts of fatty acids to give greater sudsing properties to the soap.

The words comminuted soap, as used in the specification and in the claims, include flaked soaps as well .as granulated and powdered soaps.

The words saponifiable higher fatty acid which are employed throughout the specification and in the claims include single fatty acids as well as mixtures thereof.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A method of treating comminuted soap to agglo erate soap dust particles therein into free flowing granules which comprises mixing said comminuted soap, at least about 5% by weight of a saponifiable higher fatty acid, and a sufiicient amount of alkali to saponify said higher fatty acid; and thoroughly mixing the ingredients to form well-defined granules.

2. A method of treating comminuted soap to agglomerate soap dust particles therein into free flowing granules which comprises mixing said comminuted soap, about '520% by weight of a saponifiable higher, fatty acid, and a sufiicient amount of alkali to saponify said higher fatty acid; and thoroughly mixing the ingredients to form Well-defined granules.

3. A method of treating comminuted soap to agglomerate soap dust particles therein into free flowing granules and thereby eliminate substantially all of the soap dust in .said comminuted soap which comprises mixing alkali with said comminuted soap, adding to the mixture at least about 5% by weight of a saponifiable higher fatty acid to thoroughly wet the soap particles, and thereafter thoroughly mixing the ingredients to form welldefined granules, said alkali present in sufficient quantity to saponify said higher fatty acid. 7

4. The method as described in claim 3, wherein the saponifiable higher fatty acid is a mixture of about 46 per cent oleic acid, 39 per cent linoleic acid, 3 per cent linolenic acid, and 12 per cent rosin acid.

5. The method as described in claim 3 wherein the saponifiable higher .fatty acid is red oil.

References Cited in the file of this patent UNITED STATES PATENTS 1,813,701 .Howe July 7, 1931 1,989,765 Moss Feb. 5, 1935 2,243,054 Vail :May 20, 1941 2,329,694 Bodman Sept. .21, 1943 2,388,632 Byerly Nov. 6, 1945 2,456,437 Miles Dec. 14,, 194.8 2,465,346 Bodman Mar. 29, 1949 

1. A METHOD OF TREATING COMMINUTED SOAP TO AGGLOMERATE SOAP DUST PARTICLES THEREIN INTO FREE FLOWING GRANULES WHICH COMPRISES MIXING SAID COMMINUTED SOAP, AT LEAST ABOUT 5% BY WEIGHT OF A SAPONIFIABLE HIGHER FATTY ACID, AND A SUFFICIENT AMOUNT OF ALKALI TO SAPONIFY SAID HIGHER FATTY ACID; AND THOROUGHLY MIXING THE INGREDIENTS TO FORM WELL-DEFINED GRANULES. 